JPH05106193A - Manufacture of paper, paper board and boxboard - Google Patents

Abstract

PURPOSE: To obtain paper, board and cardboard from which a product having good retention, coagulation and dehydration is formed by draining a paper stock contg. undesirable substances in the presence of a specified fixing agent and a cationic retention aid. CONSTITUTION: A paper stock contg. undesirable substances (such as unbleached pulp) is polymerized with up to 90 molar % of an ethylenic unsatd. monomer from the group of vinyl acetate, vinyl propionate, 1-4C alkyl vinyl ether, N- vinylpyrrolidone, ester, nitrile, and acrylic or methacrylic amide. The paper stock is drained in the presence of the introduced N-vinylformamide homo- and/or co-polymer (preferably with a K value of 60-90) having a hydrolytic degree of not less than 60% (preferably 70-100%) as a fixing agent and preferably a cationic retention aid such as polydiallyldimethyl ammonium chloride, to obtain the objective paper.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for making paper, paperboard and cardboard.

[0002]

From European Patent (FP) 0216387, 95-10 mol% of N-vinylformamide and vinyl acetate, vinyl propionate, C ₁ -C ₄ -alkyl vinyl ethers, N-vinylpyrrolidone, esters,
Copolymers consisting of 5-90 mol% of ethylenically unsaturated monomers from the group of nitriles and amides of acrylic acid and methacrylic acid are at least partially hydrolyzed and 30-100 mol% of the formyl groups are eliminated from the copolymer. In the form of 0.1 to 5% by weight with respect to the dry fiber,
It is known to add to pre-form stock as a wet and dry strength enhancer for paper.

US Pat. No. 4,421,602
From the specification, in papermaking, partially hydrolyzed N
-Holding homopolymer of vinylformamide-, dehydration-
And its use as a flocculant is known. The water cycle in paper mills is gradually concentrated, thus increasing the amount of anionic compounds in the reflux water, which may cause the action of the cationic polymer processing chemicals during stock dewatering and the retention of fillers or textile materials. Significantly lowers. Therefore, in order to dewater the stock with the unwanted substances together with the cationic polymer, in practice measures are taken to carry out the dewatering of this stock additionally in the presence of a binder. As the fixing agent, for example, a condensate of dicyandiamide and formaldehyde or a condensate of dimethylamine and epichlorohydrin is used (Tappi Journal, August 1988, 131-1).
(See page 34).

[0004]

The present invention is more effective than conventionally used sticking agents and, in combination with cation retainers, gives better retention-, cohesion- and aggregation than previously used combinations. It is to provide a product having a dehydrating action.

[0005]

This object is achieved according to the invention by a process for producing papers, paperboards and cardboards by dewatering the stock containing undesired substances in the presence of fixing agents and cationic retention agents. As a fixing agent at this time,
Homo- and / or copolymers of hydrolyzed N-vinylformamide with a degree of hydrolysis of at least 60% are used.

In the process according to the invention, the stock is dewatered, but for the manufacture of this stock, all the fibrous materials are used alone or mixed with one another. In practice, water is used for making the stock, which is at least partly or completely refluxed from the paper machine. Here, this is clarified or unclarified backwater as well as mixtures of such qualities. Refluxed water contains more or less large amounts of the abovementioned undesired substances, which significantly reduces the action of cationic retention agents and dehydrating agents. The content of undesired substances in such stocks is characterized, for example, using the total chemical oxygen demand (CSB-value) -parameter. The CSB-value of such a stock is 300 to oxygen.
30,000 mg, in particular 1000 to 20000 mg / kg aqueous phase of stock.

This amount of undesired substances significantly reduces the normal action of the cationic dehydration and retention agents, so long as they are used in papermaking in the absence of fixing agents.

As fibrous materials for the production of pulp, use is made of all the qualities customary therefor, such as wood pulp, bleached and unbleached pulp and stocks from all annuals. Examples of the wood pulp include ground wood pulp and thermomechanischer pulp.
stoff; TMP), chemo-thermo-mechanical pulp (CTMP), pressure groundwood (Druckschliff), semi-pulp (Halbzellstoff), high yield-pulp and refined mechanic pulp (RMP). Examples of pulp include sulfate, sulfurous acid and zoda pulp. Unbleached pulp, which is also excellent as unbleached kraft pulp, is used in particular. Suitable annuals for making furnish are, for example, rice, wheat, sugar cane and kenaf.
For pulp production, waste paper can be used alone or in a mixture with other fibrous materials.

Pulps of the type mentioned above contain more or less large amounts of undesired substance forms, which, as indicated above, are CS.
The B-value can also be measured using the so-called cation demand. The cation demand refers to the amount of the cationic polymer required to bring a certain amount of backwater to the isoelectric point. The cation demand is very significantly attributed to the composition of the respective cationic retention agent used for the measurement, so to standardize it the West German patent (DE-P
S) Polyamidoamines (see Polymer I below) from adipic acid and diethylenetriamine obtained according to Example 3 of 2443416 and grafted with ethyleneimine and crosslinked with polyethylene glycol dichlorohydrin ether were used. Pulps with undesired substances have the abovementioned CSB-values and polymer I
It has a cation requirement of 50 mg / l backwater or more.

According to the invention, N-, which has a degree of hydrolysis of at least 60%, is used as a fixing agent for stocks containing unwanted substances.
Hydrolyzed homo- and / or copolymers of vinylformamide are used. Such polymers are known, for example, from EP 0216387. To produce them, for example, N-vinylformamide is polymerized and the formyl group is eliminated from the polymer by hydrolysis in the presence of acid or base. N-
Removal of the formyl group from the polymer containing the polymerized vinylformamide unit results in the formation of vinylamine units in the polymer. The degree of hydrolysis of the polymerized N-vinylformamide is at least 60 mol%, especially 70 to 100 mol%.

The copolymer used as the fixing agent is N
95 to 10 mol% vinylformamide and ethylenically unsaturated monomers from the group of vinyl acetate, vinyl propionate, C ₁ -C ₄ -alkyl vinyl ethers, N-vinylpyrrolidone, esters, nitriles and amides of acrylic acid and methacrylic acid. Derived from copolymers containing 5 to 90 mol% of polymerisation, the formyl groups in the copolymer are at least 60%, in particular 70 to 100% hydrolyzed and are therefore present as amino groups. Esters of acrylic acid and / or methacrylic acid are derived from alcohols having 1 to 6 carbon atoms.

A) 100 to 10 mol% vinylformamide and b) 0 to 90 vinyl acetate and / or vinyl propionate.
% Of the formyl groups from the polymerized units a) of the copolymer, after polymerization.
Preference is given to using hydrolyzed polymers in which 100% and 60-100% of the acetyl- and / or propionyl groups from the polymerized units b) have been eliminated. Removal of the formyl group from the copolymer is carried out especially with hydrochloric acid or caustic soda solution and is, for example, 20 to 1
It can be carried out in the temperature range of 00 ° C.

However, the elimination of the formyl group can also be carried out using hydrogen chloride or hydrogen bromide under exclusion of water.
At this time, an amino group is produced from the N-formyl group of the copolymer by elimination of carbon monoxide. Upon the action of acids or bases on the copolymers of N-vinylformamide and acrylonitrile, methacrylonitrile, N-vinylpyrrolidone and C ₁ -C ₄ -alkylvinylether, the comonomers of N-vinylformamide are chemically largely unchanged. However, the polymerized N-vinylformamide is at least partially hydrolyzed. Upon copolymerization of N-vinylformamide with vinyl acetate and / or vinyl propionate, a product hydrolyzed at a temperature of 50 ° C., for example by the action of hydrochloric acid, is obtained. Vinyl propionate is not hydrolyzed, whereas the polymerized N-vinylformamide is hydrolyzed to at least 60%. When a copolymer of N-vinylformamide and vinyl acetate or vinyl propionate is treated with caustic soda solution at a temperature of 50 ° C., formyl groups are also introduced from the polymerized N-vinylformamide. From vinyl acetate or vinyl propionate, acetyl- or propionyl groups are eliminated from the copolymer almost equally. The degree of hydrolysis of the polymer depends mainly on the amount of acid or base used and the temperature during hydrolysis.

N-with a hydrolysis of at least 60%
Homo- and copolymers of vinylformamide have K-values of 30 to 150, in particular 60 to 90, according to Fikentscher (measured in 5% saline in 0.5% by weight polymer concentration and 25 ° C. temperature). In the process according to the invention, the sticking agent is used in conventional amounts, i.e. 0.02 to 2, relative to dry stock, in particular 0.
It is used in an amount of 05 to 0.5% by weight.

As cationic retention agents it is possible to use all commercially available products for this purpose.
In this case, this is, for example, polyethyleneimine, polyamines having a molecular weight of 50,000 or more, polyamidoamines modified by grafting of ethyleneimine in some cases, polyetheramines, polyvinylimidazole, polyvinylpyrrolidine, polyvinylimidazoline, polyvinyltetrahydro. Pyridine, polydialkylaminoalkyl vinyl ethers, protonated or quaternized forms of polydialkylaminoalkyl (meth) acrylates. Further suitable compounds are, for example, polydiallyldialkylammonium halogenides, especially polydiallyldimethylammonium chloride. Particularly preferred retention agents are: adipic acid and polyalkylenepolyamines such as diethylenetriamine, grafted with ethyleneimine and from West German Patent (DE-PS) No. 2
Polyamidoamines crosslinked with polyethylene glycol dichlorohydrin ethers according to 434816 or with epichlorohydrin, and commercial polyethyleneimines and copolymers from acrylamide or methacrylamide and dialkylaminoethyl acrylates or -methacrylates, for example Copolymers from acrylamide and N, N-dimethylaminoethyl acrylate or copolymers from acrylamide and N, N-diethylaminoethyl acrylate. Basic acrylates are present in neutralized or quaternized form, especially with acids. The quaternization can be performed using, for example, methyl chloride or dimethyl sulfate. The cationic retention agent is K- according to Fikentscher (measured at a polymer concentration of 0.5% by weight and a temperature of 25 ° C. in 5% saline).
It has a value of at least 180. The cationic retention agent is p
H-value of 4.5 and at least 4 mVal / g of polyelectrolyte
Has a charge density of. The charge density depends on the horn (D.
n), Polyethylenimin / Phys. Chem. Prop. and Appl.
(IUPAC) Polymeric amins and amonium salts (Perga
mon Press Oxford and New York, 1980, pp.333-355)
Measured by

According to the invention, the dehydration of the stocks containing undesired substances is carried out in the presence of hydrolyzed N-vinylformamide polymers as fixing agents and cationic retention agents customarily used. It is advantageous to add to the stock first the sticking agent and then the holding agent. However, they can also be supplied to the stock at the same time. It is only important that the stock is dehydrated in the presence of a sticking agent and a holding agent. The retention agent is used in an amount of 0.01 to 0.2% by weight, based on the dry stock. The ratio of sticker to retention agent is generally 1: 2 to 5: 1. Compared to commercially available combinations of sticking agents and cationic retention agents, the process of the invention provides improved retention and rapid dewatering of stock.

[0017]

EXAMPLES "Parts" shown in the examples represent "parts by weight",
"%" Is "% by weight" of a substance.

Dehydration time determination: 1 liter of the suspension of the fibrous substance to be tested is dehydrated in a Schopper-Riegler-Testgeraet, respectively. The time taken for 700 ml of water to flow out from the Shopper-Riegler-tester was shown as the dehydration time.

The chemical oxygen demand, CSB-value was determined according to German Industrial Standard (DIN) 38409.

The transparency of the backwater is measured by the Zeiss-Spektralfotometer PM7.
Was measured. This is a measure of the retention of fines and filler material. This is indicated by "%". The higher the transparency value, the better the retention.

Cation demand: The amount of polymer I required to bring 1 liter of backwater to the isoelectric point. Measure the final point with a horn, Progr. Colloid & Polym. Sci. B
d. 65, 251-264 (1978).

The K-value of the polymer is determined by Fikencher,
Cellulose-Chemie, Band 13
48-64 and 71-74 (1932) in 5% saline at a temperature of 25 ° C. and a polymer concentration of 0.5% by weight. At that time, K = k · 10 ³ .

Cationic Retention Agent Used Polymer I: West German Patent (DE-PS) No. 2434816
Polyamidoamine consisting of adipic acid and diethylenetriamine, grafted with ethyleneimine and crosslinked with polyethylene glycol dichlorohydrin ether as described in Example 3 of the specification.

Polymer II: Polyamidoamine consisting of adipic acid and diethylenetriamine, grafted with ethyleneimine and crosslinked with epichlorohydrin.

Polymer III: Commercially available high molecular weight polyethyleneimine adjusted to pH-7.5 with formic acid.

Polymer IV: A copolymer of the metochloride form with a K-value of 220, consisting of 70% acrylamide and 30% N-dimethylaminoethyl acrylate.

The following were used as fixing agents: Polymer A: a homopolymer of hydrolyzed N-vinylformamide having a degree of hydrolysis of 96% and a K-value of 75.

Polymer B: N-vinylformamide 70
% And 30% of vinyl acetate, and polymerized N-
A copolymer in which 96% of the formyl groups of vinylformamide and 68% of the polymerized vinyl acetate groups are hydrolyzed.
The K-value of the hydrolyzed copolymer was 75.

Polymer C: as a comparison with the state of the art,
A commercial condensate composed of dicyandiamide and formaldehyde.

Polymer D: K-value 100, as a comparison
Commercially available homopolymer of diallyldimethylammonium chloride.

Example 1 1 liter of newsprint material containing 2 g / l of stock containing pulpwood and carion contained a pH value of 7 and a pulverization degree of 68 ° S.
In R (Shopper-Riegler), a stock with many sources of undesired substances was produced, each with 0.2% of the sodium salt of humic acid added as the undesired substance. Then the first
The amounts of Polymer A or Polymer C listed in the table were each dispensed into the stock containing the undesired substance, after which 0.06% of the retention agent listed in Table 1 was added and the dehydration time was measured. The results obtained at that time are also shown in Table 1.

Table 1 Dewatering time [sec] Fixing agent Polymer A Polymer C (comparative) Amount 0.2% 0.4% 0.2% 0.4% Retention agent Polymer 1 52 38 70 66 Polymer 2 44 34 77 63 Polymer 3 51 33 86 65 65 Polymer 4 21 20 30 27 Example 2 As a stock material model, a stock material concentration of 2 g / l containing pulpwood pulp and kaolin was used at pH-value 7 and ground. Used at 68 ° SR. The stock further contained 3% sodium lignin sulfate as an undesired substance. To each sample of this stock was added the amount of fixing agent listed in Table 2 followed by 0.06% polymer as a cation retention agent. The dehydration time was then measured with a Shopper-Riegler-tester and the clarity of the filtrate obtained was measured.
In addition, Rapid-Koethen-Gerae
On t) a paper having a plane weight of 70 g / m ² was formed and its ash content was measured. Table 2 shows the amounts used and the results obtained using them.

Table 2 Dehydration time [sec] Clarity Ash [%] 0.2% 0.4% 0.2% 0.4% 0.2% 0.4% Polymer A 112 110 18.4 27.0 11.1 13.8 (Pieces (According to the invention) Polymer D 114 113 16.3 22.8 10.6 12.0 (comparative) without fixing agent 116 15.8 11.6 Example 3 75% wood pulp, 25% pine sulphate pulp, 35% china clay with a stock concentration of 5 g / l. A stock having a grindability of 25 ° SR and having a pH-value of 7 was processed on a test paper machine at a machine speed of 80 m / min and a flat weight of 60 g /
Make paper with m ² . The stock is 0.2% sodium salt of humic acid as an unwanted substance and Polymer 1 as a retention agent.
It contained 0.2%. Under this condition, the dehydration time is 12
4 seconds and ash-hold was 57.4%. In a further test, the stock was added with the polymers listed in Table 3. The results obtained are shown in Table 3.

Table 3 Dehydration time [sec] Ash [%] None 124 57.4 Polymer 1 (comparative) 81 71.1 Polymer C (comparative) 45 75.3 Polymer A 12 88.4 Example 4 As a model substance A newsprint stock with a stock concentration of 2 g / l containing sawdust pulp and kaolin was used with a pH-value of 7 and a crushing degree of 68 ° SR. To this, 3% sodium lignin sulfate was added as an undesired substance. The stock thus obtained was dewatered in a Shopper-Riegler apparatus. The results obtained without the addition of retention- and dehydrating agents, and at the same time the results obtained with the addition of 0.2% of the polymers listed in the table as fixing agents, respectively and subsequently 0.06% of the polymers as retaining agents. Is shown in Table 4.

Table 4 CSB-value (O ² mg / l) Cation demand of polymer 1 (mAEqu / l) None 1386 1750 Polymer 5 (comparative) 1408 1400 Polymer A 1222 1270 Polymer B 1301 1220

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Primo Lorenkak Federal Republic of Germany Rootwitzhischauf Enberner Weak 32 (72) Inventor Michael Kleener Mannheim 1 Ithleben Werk 8 (72) Inventor Norbert Sendhoff Germany Grieunschyutatt Auf del Valt 16 (72) Inventor Walter Dentzinger Germany Sichpayer Wolmserland Schutlerse 65 (72) Inventor Heinrich Hultmann Germany Frürnheimer Weinheimer Schutler 46

Claims (6)

[Claims] 1. A hydrolyzed N having a stock containing undesired substances dehydrated in the presence of a binder and a cationic retention agent and having a degree of hydrolysis of at least 60% as a binder.
A process for making paper, paperboard and cardboard, characterized in that homo- and / or copolymers of vinylformamide are used. 2. A degree of hydrolysis of 70 to 100% as a fixing agent
The method of claim 1, wherein a hydrolyzed homopolymer having is used. 3. An ethylenically unsaturated monomer from the group of vinyl acetate, vinyl propionate, C ₁ -C ₄ -alkyl vinyl ethers, N-vinylpyrrolidone, esters, nitriles and amides of acrylic acid or methacrylic acid as fixing agents. Of 90% to 90% by mole, and the degree of hydrolysis of the N-vinylformamide unit introduced by polymerization is 70 to
The process according to claim 1, wherein a copolymer of 100% hydrolyzed N-vinylformamide is used. 4. A) N-vinylformamide 100-1
0 mol% and b) vinyl acetate and / or vinyl propionate 0-90
Elimination of 60-100% of formyl groups from polymerized units (a) and 60-100% of acetyl- and / or propionyl groups from polymerized units (b) of the copolymer and subsequent polymerization of the mol%. The method according to claim 1, wherein a hydrolyzed polymer obtained by 5. The process according to claim 1, wherein the polymer has a K-value of 30 to 150 (measured by H. Fikencher at 25 ° C. in 5% saline solution and 0.5% by weight polymer concentration). 6. The polymer has a K-value of 60-90.
The method according to claim 5.